It is strange that in this era of weak and shallow Christian faith, there should be so many who claim that the Christian ought to imitate Christ in all aspects of His life and evangelism: specifically that Christians ought to seek-out the worst of non-Christians and the worst of sinners for their evangelical work. That is, for the Christian to immerse himself in all that is most dangerous and seductive and destructive about modern life and culture.
This kind of things often strikes me as either a species of spiritual pride - when applied to oneself, or demonic advice - when suggested to others.
What was possible and necessary for Jesus, may be foolish, impossible and to-be-avoided for feeble Men - and in the category of feeble I would include almost all modern Christians.
To balance the Scriptural exhortations that none be excluded from evangelism, there are others which emphasize the need to shun extreme sin that we be tempted and fall: the 'he who touches pitch will be defiled' idea which motivates the separateness of groups such as some Anabaptists (Amish).
This sees humans as such weak vessels of truth as easily to be shattered by the world, the flesh and the devil.
So if Christians throw themselves into living in environments dominated by powerful and continuous temptations of lust, or worldly politics (Leftism), or power, or whatever - then they must be solid in their strength of faith.
It is glib to assert one-sidedly truths (and they are truths) such as that with God anything is possible and that it is the Holy Spirit which does all evangelical work. That there is indeed danger from one-sided optimism in the possibilities of evangelism and the security of one's own faith is shown by advice in the Epistles concerning the need for a Christian to separate from corrupting influence (for example to expel unrepentant corrupters from the congregation, to shun heretical preachers, and so on).
The fact is that while on the one hand we can have assurance of salvation, on the other hand we are engaged in an on-going spiritual warfare by which evil can 'turn' the believer to reject salvation.
(Active rejection the only way that a real Christian adopted into God's Holy Family can lose salvation, yet such rejection is something which has happened, does happen and will no doubt continue to happen. While the good family never rejects a repentant prodigal Son, no matter what he has done; the son can reject the family by refusal to repent.)
So far as I can tell, Christianity is always a middle way. Not a compromise between extremes, but the true path lies between extremes.
Peril is both to right and to left.
Promiscuous evangelism may be courting disaster, yet rigid separatism is usually fatal to a Church (and, anyway, prohibited by Scripture).
The Eastern Orthodox - at their height - were acutely aware that spiritual ambition, the desire for sanctification, was spiritually hazardous; and that there was a tendency to over-reach and try to hurry the process.
So, many monks wanted to be hermits and strive in solitude for the highest levels of theosis; but were not allowed unless they had proven their spiritual strength by many years of ascetic practice under supervision from a spiritual supervisor, who had himself been through the same process going back to the Church Fathers and Apostles.
Thus, spiritual ambition - while itself admirable - opens to spiritual pride; and there are many tales of hermits who succumbed to demonic temptations and became forces for evil: for example heretics and corrupters.
We live at a lower spiritual level nowadays, but consequently may be dragged-down by much milder lures from Men, not demons.
The desire to evangelize the worst of sinners may be motivated by spiritual pride, or a public mask for wickedness just below the surface of faith, which covertly seeks its own corruption - to go among egregious sinners secretly hoping to share their sin.
The desire to evangelize 'the world' may lead people to missionary activity beyond their strength, which is corrupted into the ever more powerful worldly desire to alleviate poverty, heal the sick, change the government and put an end to war - and the temptation to delay, set-aside, and finally abandon (in reality, whatever facade may be retained) the primary and absolute requirement to bring people to Christ. There are many examples of this among the most famous of politically active 'Christians'.
In sum, a proper recognition of the weakness of our faith would suggest that, although a middle way must always be sought, for us moderns in an ever more pervasively secular and increasingly anti-Christian world of moral inversion, the middle way lies somewhat further towards separatism than our the currently prevalent (and too often corrupting) ideal of recklessly promiscuous evangelism.